## Bootstrap parameters
Number of resamples and number of cores for `mcMap()`.
```{r}
set.seed(575)

cores <- 4
```

## Subset data to voting-age population
```{r}
density    <- filter(density,    age >= 18)
turnout    <- filter(turnout,    age >= 18)
votechoice <- filter(votechoice, age >= 18)
```


## Subset to recent years

```{r}
yrs <- seq(1976, 2020, 4)

density    <- filter(density, year %in% yrs)
turnout    <- filter(turnout, year %in% yrs)
votechoice <- filter(votechoice, year %in% yrs)
```

## Drop missing values in voting bloc variable
```{r}
density    <- tidylog::drop_na(density, all_of(covariate))
turnout    <- tidylog::drop_na(turnout, all_of(covariate))
votechoice <- tidylog::drop_na(votechoice, all_of(covariate))
```
